1. Field of the Invention
2. Description of the Prior Art
Vertical feed mixers of various forms are known and, in particular, vertical feed mixers for mixing round bales of hay or haylage of any size, including large and small bales with other animal feed stuffs including corn, silage, commodities, by-products and concentrates are known. Previous vertical feed mixers have a mixing chamber with a vertically mounted auger having a helically shaped expanding periphery that is narrowest at a top and increases in size towards a base. The mixing chamber has a door in a side wall thereof. The door has a closed position and an open position and is used to allow feed that has been mixed to exit the mixer. With previous mixers, when the mixing process has been completed, the door is moved to the open position and a large portion of the feed that has been mixed exits from the mixing chamber through the door. Usually, the mixing chamber is not completely emptied and a sizeable portion of the feed remains within the mixing chamber. The feed must either be removed manually by an operator of the mixer or remains in the mixer where it is ultimately wasted or becomes mixed in with more feed that is subsequently mixed within the mixer. When different types of feed are mixed in different batches, it is not desirable to have a sizeable amount of feed remaining in the mixer as that feed might contaminate a subsequent batch. The feed remaining in the mixer reduces the efficiency of the mixer and makes the mixer much more expensive to operate.